Static stopper

ABSTRACT

A time regulated switching device is made applicable to screen apparatus operation control signals so as to prevent accidental control of the apparatus by spurious signals randomly interposed with already sequentially-generated control signals. A timed cam control of switch activity in the device directed by the control signals before they are effective to initiate desired functions of the apparatus determine an interval of delay in which the control potential of spurious signals is dissipated. Energizations of means engaging a clutch adapted to transfer a drive from a timing motor which displaces the cam against a bias thereon toward restored disposition thereof, occur in response to the control signals, and are coordinated with control of motor energizations by the cam for assuring the effectiveness of further valid control signals in regulating operations of the apparatus after the delay interval.

Sprinkle United States Patent [541' STATICSTOPPER 5..

72] Inventor: Leland w. Sprinkle, Springfield, Va.

[73] Assignee: The United States of America as represented by the Secretary of the Interior 1 [22] Filed: Oct. 27, 1971 [21 Appl. No.: 192,901

[52] US. Cl. ..307/l33, 318/467, 318/486,

- 353/19 [51] Int. Cl.. .L .1102!) 1/16 [58] Field of Search..307/l32 M, 133; 318/467, 486; 8 353/19- [56] References Cited UNITEDSTATES PATENTS 3,440,445 4/1969 Kusa ..307/133 UX 3,217,595 11/1965 Gallina ..353/107 3,526,791 9/1970 Codichini ..307/133 X 3,493,835 2/1970 Hellman ..307/133 X 3,579,096 5/1971 Buchanan ..307/133 X [451 Oct. 31, 1972 Primary Examiner -Benjamin Dobeck Attorney-Ernest S. Cohen ABSTRACT signals before they are effective to initiate desired functions of the apparatus determine an interval of V delay in which the control potential of spurious signals is dissipated. Energizations of means engaging a clutch adapted to transfer a drive from a timing motor which displaces the cam against a bias thereon toward restored disposition thereof, occur in response to the control signals, and are coordinated with control of motor energizations by the cam for assuring the effectiveness of further valid control signals in regulating operations of the apparatus after the delay interval.

5 Claims, 4 Drawing Figures ,4 '1 ,8: lllllllllllllllllll' I l PATENTEDMI r I 3.701.905. I sum 1 mfg) STATIC STOPPER.

The invention is in an improved control signal testing arrangement in an automaticallyvcontrolled apparatus of an integral system. This improvement functions as a screen for apparatus conditioning control signals which the system generates,'and renders ineffective spurious signals it has detected. More specifically, those signals arising randomly" in the course of a normal system operation capable of I controlling apparatus of the sy's'tem which'ordinarily responds to control signals generated in a predetermined timed sequence are allowed to dissipate their potentiality for control without disrupting or interferingwith the normal operation of such apparatus- Disclosed herein by way of example is an adaptation of a preferred embodiment :of theinvention to an audio-visual presentation system invented by Leland W. Sprinkle, the inventor in the instant case, and which is the subjectof a patent application Ser. No. 30,396, filed Apr. 21, 1970. Operational control input for the Sprinkle system derives from a recording which carries a sequence of audio messages to be delivered in connection with the showing by light projection of a series of transparency slides, together with a sequence of inaudible signals. for coordinating such audio-visual presentation, including the control of the operation of an automatic slide projector of the system displaying the aforesaid slides. In addition to sequencing the functions of the projectorls slide changing devices so as to secure atimely display of the slides with respect to the delivery of the audio messages, these coordinating signals determines arequisite operational termination sequence for the system wherein completion of each audio-visual presentation is followed by a system reset procedure which culminates in reaching a starting condition for the system. A low frequency control signal of the sort disclosed in the Sprinkle application, i.e.', 30 Hz, is normally distinctive, and generally outside the range of signals encountered in conventional audio message recordings. Nevertheless, any occurrence of rise to a control action almost invariably has a disruptive effect on. proper operation, and is undesirable. Such signals are often present in electrical static, and occasionally are found mixed with the audio frequencies constituting the sound of the human voice. It is evident that a slide change operation in response to a spurious control signal may bring the next slide into the light chamber of the projector during a delivery of a message intended solely for the side exchanged. To eliminate practically the likelihood of an operational interference, as indicated herein, without resorting to extensive and complex editing for the preparation of the control recording, the present invention accepts the rec'ordings spurious signals as input for the system, but blocks such signals from exercising'any relevant control over system functions.

In the present invention any system control input having the characteristics of a normal control signal,

i.e., the 30, cycle frequency, or an instantaneous spikelike signal, initiates action towards a full sequential operation. However, relevant functional response by the system .to any such signal is delayed for a predetermined interval. Moreover, this interval of delay is settable so as to allow the completion or dissipation .therein of any probable spurious signal.

Whereas, a spurious signal does not bring about a meaningful functional response for the system, all scheduled control signals initiating the aforesaid sequential operation are of such length as to extend beyond the interval of delay and are effective to give rise to a desired response. Use is made of an adjustable switch controlling camming mechanism in the preferred embodiment of the invention'to evolve the unique sequencein which a time delay reflecting the probable duration of the most extended spurioussignal is followed by a requisite functional sequence. One form of a prior art device which delays a relevant functional response is disclosed in US. Pat. No. 3,2l7,5 95, issued Nov. 16, 1965, to H. Gallina, as part of a transparency slide magazine positioning control mechanism for a projector. The patented device employs a coil spring tensioned lost motion clutch structure which transfers a motor drive to a friction wheel adapted for engagement with the slide magazine following an inter-.

val of delay set to allow release of the slide magazine from an automatic drive generally applied thereto. A regulator of an appropriate delay, and the subsequent timing of further functions of the present invention, as it is disclosed herein, is more in the nature of a time controlled drive to a notched camming element of the type shown in US. Pat. No. 2,976,471, issued Mar. 21,

1961, to J. L. Harris. However, the regulating camming element of the present invention is uniquely adapted herein to give rise to a new cooperative relationship with a special control circuitry for automatically effectuating all slide changing and subsequent programmed sequencing of projector functions. i

It is therefore an object of the present invention to provide in a timed signal controlled mechanism a safeguard against signals untimely supplied thereto which would otherwise adversely affect the control.

This and other objects of the invention will be more clearly understood from the following description of a preferred embodiment of the invention considered together with the'accompanying drawing wherein:

FIG. 1 is a detailed schematicshowing of circuitry and components operatively associated therewith constituting a preferred embodiment of the invention; and

FIGS. 2A, 2B and 2C are schematic showings of a cam operated switching arrangement, having utility in the circuitry appearing in FIG. 1, which respectively illustrate pertinent switching conditions of the arrangement during an operation sequence of the invention.

Disclosed herein is a form of the present invention made applicable in cooperation with the apparatus of the previously identified Sprinkle system which is adapted to function sequentially in response to control signals transmitted thereto from an automatically operablesignal source of the system. Through such cooperation all valid control signals emanating from thesource are fully effective in the management of the apparatus whilst spurious signal arising from the source are made ineffective to consummate such control. Exemplary of one apparatus of the system in which a preferred embodiment of the invention has utility is a transparency slide projector schematically shown in FIG. 1 as having a slide changing arrangement 10, comprising slide changing devices 12, and a cyclically indexed circular slide carrier tray 14. Control devices 12 obtains a stepped rotation for tray 14 in coordination 3 with dispositions thereof at predetermined intervals which allow manipulation of the slides therein for projection and viewing. Sequencing of the aforementioned dispositions, as well as the indicated tray displacement, is regulated by cyclically operable control elements of devices 12 including a plurality of cams which are loosely mounted on a drive shaft, and adapted to be motor driven by way of the shaft through a clutch connection. Reference to the disclosure in US. Pat. No. 3,276,314, issued Oct. 4, 1966, to H. T. Robinson, of a slide projector which has utility in connection with the present invention, provides a detailed description of the aforesaid cam control and the drive therefore. The Robinson patent reveals this drive as operable when an electromagnet is momentarily energized, by a manual or remote controlled push button, andreleases a clutch spring driving connection between an activated motor and the aforementioned cam drive shaft-for rotation thereof through a single revolution or cycle, whereafter the clutch disengages and disconnects the drive to the control. Rotation of this cam control initially effects closure of a shutter over the projected image and enables operation of a mechanism which lifts the slide at I the viewing position on the optical axis and returns it to carrier tray 14. Thereafter, an indexing mechanism is enabled with release of the carrier tray for rotation which positions its next slide compartment over the optical axis of the projector. Following effectuation of the indexing step a mechanism is made operable to lower a slide from the newly aligned compartment into the path of the optical axis, and subsequently the shutter thereon is opened to complete the functions of the cycle. The slide projector is additionally represented in FIG. 1 by a cool down blower fan 16, and a projection lamp 18, which are several components thereof also functionally associated with the operation of the present invention, as will be hereinafter more fully disclosed.

Operational control signals for use in the projector apparatus are derived from a recording, and in this instance from a magnetic tape recording prepared in accordance with the requirements of an audio-visual program presentation for which the Sprinkle system is normally employed. Reference to the previously identified patent application on this system for a more complete disclosure of the tape recording made applicable herein reveals such a tape as having recorded thereon requisite messages of voice, music, etc., together with signals which when read-out and transmitted to the projector are adapted to determine a timing of the sequence wherein slides are projected. This timed sequence in effect schedules the visual presentations so as to provide therefor accompanying audio presentations of the aforesaid messages. The signals are therefore recorded at those intervals which are sufficient to accommodate during their times the audio presentation of the recorded messages as an accompaniment to the I pictures projected. Schematically represented in FIG. 1

is tape recorder 20 comprising apparatus of the system having a circuit arrangement in which a synchnonous motor and magnetically locked tape guiding roller are operable when energized to obtain from a tape recording supplied therein a read-out of messages and signals,

in the nature of that heretofore indicated, to an amplification component 22, and thence through diverging circuits to sound reproducing and control signal sensing components. Uniform amplitude, low-frequency control signals which the tape supplies are, with the exception of their duration, which is hereinafter more fully explained, the same as the 30-cycle control signals of approximately a 0.1 second duration adapted for use in the Sprinkle system. Such low-frequency signals are essentially ineffective in the audio components, but upon their detection in a suitable 30 cycle filter circuit 26, and subsequent intensification in an amplifier 28, they are effective in a sensor-trigger arrangement constituting a transceiver 30. In response to this control signal input to transceiver 30 signals are produced in activating circuits for pertinent functional units of the projector and tape recorder.

Accordingly, transceiver 30 is routinely supplied by amplifier 28, transmitting through electrical connections including a pair of leads 31, 32, all signals passed by filter 26. As was hereinbefore indicated, any spurious or random 30-cycle signals, as well as spikelike signals having no frequency characteristic, such as have their origin in environmental static, power supply interference, or any other acoustical or electrical noise occurring during the preparation of the tape recording, are also read from the tape and transmitted. In a manner to be hereinafter more fully set forth, the present invention functions to avoid the deleterious consequences of the noise signals received in transceiver 30; primarily the premature triggering of a slide changing operation in the projector apparatus which would disrupt the proper sequencing of the audiovisual presentation system and result in the mismatching of all the subsequent projected pictures and audio messages of a program. Transceiver 30 contains a cup-like enclosure 34 wherein a pair of photocells 36 and 38 are arranged with the light sensi tive elements thereof set facing a small lamp 40 for which a power circuit is completed through control signal supply leads 31 and 32. A pair of thyristors 42 and 44 in transceiver 30 responds to the light sensors of enclosure 34 through separate gating circuitries 46 and 48, wherein the respective photo-cells 36 and 38 are series connected with current limiting, firing control resistors 50 and 52, respectively. However, continuity in the conductive path of the thyristor 44 gating circuitry 48 is determined by the operational status of a camoperated normally closed switch 54. This conductive path is traceable from switch leads 56 and 57 to the respective pin-socket junctions a and b at the terminal of a plug connector 58 for internal components of the aforesaid system, and on leads 60 and 61 from the connector terminals to appertaining elements in transceiver 30, in a manner and for a purpose to be hereinafter more fully disclosed. When thyristor 44 is triggered and conductive, it in turn functions as a switch which closes a power circuit, completed through a-c cource 63, for energizing slide changing devices 12 in the projector. This energization circuit is traceable by way of leads 62 and 64, which join the thyristor power terminals to the respective connectors 66 and 68 at separate contact arms of a two-condition latching relay 70, relay contacts 72 and 74, respectively, adapted to be engaged by the aforesaid contact arms, and further leads 76 and 78, extending between slide changing devices 12 and the respective relay contacts.

. I l On the other hand, thyristor 42 is adapted upon conduction to completea power circuit wherein an electri cal clutch engaging mechanism 80 is activated when energized This energiza tion circuit is traceable by way of leads 84 and 86, which connect clutch engagingmechanism 80 across the terminals of pin-socket junctions d and 0, respectively, of plug connector 58, and further circuitry leads 88, 90, 92, 94 and 96, wherein a double pole-double'throw circuit selecting switch 98,

nector. Application of a-c power to the energization circuit is indicated on a switch panel by the glow of a neon lamp 99 which byway of its connections between the terminals of junctions d and c is energized when thyristor 42 is conductive in the circuit through switch 98. In the event the audio-visualpresentation system employing the preferred embodiment herein is to be operated. independently of the present invention, switch 98 is adjusted as indicated by the dashed line showing in FIG. 1 so as to maintain an open circuit condition in the power circuit for clutch engaging mechanism 80, and prepare a shunt circuit, including leads 102 and 104, which leaves full control of thyristor 44 to the output of amplifier 28 by disabling the control by cam-operated switch54 over thyristor gating circuitry 48. Power supplied to clutch engaging mechanism 80 is also rectified and smoothed by the further provision in its energizing circuit connections to power source 100 of a series connected diode 106 and a parallel connected capacitor 108, so as to avoid possible clutch rattling with the onset of each power application to that energizing circuit.

Clutch engaging mechanism 80 is operable to transfer the torque of a synchronous timing motor 120 to a drive shaft 122 of an operations controller schematically represented in part in FIG. 1 by its camming surfaces 124 and 126, which are shown in engagement with the previously mentioned normally closed slidechange control switch 54, and a normally open switch 130, respectively. The circuit controlling status of switch 130 determines the operational state of the timing motor energization circuit wherein a further thyristor 132 functions as a switch. More specifically, trigger c'urrent appears in a gating circuit 133 of thyristor 132 when closure of switch 130 applies power thereto supplied from source 100 through connections to the terminals of pin-sockets d and e of plug connector 58, and terminal leads 134 and 136, which by way of the conductive field windings of motor 120, and a lead '138 connected at a' motor terminal, complete a power circuit to the thyristor gating terminal through further leads 140, and 144, current limiting, firing control resistor 146 connected therein, and the thyristor power terminal connected to lead 136. When thyristor 132 is thus triggered, the conduction established therein activates an energization circuit for motor 120 which is traceable through thyristor power leads 136 and 148, and those leads connected thereto heretofore identified as applying a-c power source to the motor terminal leads 134 and 138. Interposition of a thyristor switch in the motor control circuit effectively limits current therein during switching operations which avoids damaging arcing in switch 130, and thus also reduces audio interference.

A fourth thyristor 160, appearing in FIG. 1, is' operable in connection with the present invention when it is conducting in response to a signal derived upon the restoration of slide carrier tray 14 to its initial disposition following completion of a presentation of the audio-visual program. Reference again to the previously identified Robinson patent shows the circularity of this sort of tray as characterized by two concentric shells joined by generally radial spacers forming equally spaced compartments, which are respectively numbered 0, and 1 through 80, inclusive. Individual slides are separately received, and maintained in the respective compartments between showings thereof. This construction of tray 14 facilitates the slide changing operations directed by devices 12 when responding to transceiver output on leads 62 and 64, as was previously disclosed. Thus, each of the respective slides is individually lowered into the path of the projectors optical axis, and subsequently lifted back into its compartment in the tray before an indexing operation steps the tray through a rotary displacement which locates the next slide for a showing thereof. After presentation of the last picture transparency slide is completed along with the play back of its taped message, that slide is restored to tray 14, and following a short interval of projector inactivity, with a possible musical accompaniment, tape read-out provides an extended slide change control signal. The corresponding extended output from transceiver 30 maintains a continuing operation of slide changing devices 12 wherein these devices act at intervals of about one second apart to accomplish the changes of opaque slides set in the tray to fill all compartments after the last picture transparency slide of a program. Following return of a slide to cornpartment 80, the subsequent indexing which takes tray compartment 0 into alignment with the optical axis also displaces a magnet 162, affixed to the outer shell of tray 14, in a path which crosses an end of an electromagnetic coil 164. An operational termination signal thus generated in coil 164 is transmitted on leads 166 and 168 to an amplifier 170 which responds in turn I mine the circuit controlling status of latching relay 70.

Accordingly, conduction in thyristor 160 is enabled when a control signal in circuitry comprisingleads 172 and 174 energizes lamp 180, and the resultant light on photocell 182 in the thyristor gating circuit comprising leads 184 and 186, and including current-limiting firing control resistor 188, lowers photocell resistance sufficiently to trigger this gating circuit. Leads and 192 from the power terminals of thyristor 160 are connected to an electromagnet 196 of relay 70, which is thusly energized upon conduction of the thyristor. Providing an auxiliary control for energizing electromagnet 196 is a stop button 202 in a power circuit comprising leads 204 and 205. A second electromagnet 198 of relay 70 is energizable by a start button 206 in a power circuit comprising leads 208 and 209.

Electromagnets 196 and 198 are energizable alternately whereby they are operable to pivot the contact arms of relay 70 between engagement with a first set of fixedcontacts 210, 72, 74, and 212 to 214, and engagement with a second set of fixed contacts 218 to 223, inclusive. Connections to a source of electrical power represented by encircled positive and negative signs are completed in circuits to the several operating components of the projector and tape recorder by way of the fixed contacts engaged by the relays contact arms. Thus, the energization of electromagnet 198 pivots the relay contact arms so as to engage fixed contacts of the relay from which circuitsare completed enabling an operational control sequence of the audiovisual apparatus. The subsequent energization of electromagnet 196 shifts the relay back to an initial disposition thereof so as to complete circuits through fixed relay contacts which enable circuits initiating a concluding segment of the operational sequence. Relay 70 is constructed such that it is mechanically latched in its start or stop state to which it is set by activation of one electromagnet until reset by the activation of the other electromagnet. Descriptions and explanations in further detail of the structure and cooperative relationships which characterize the circuits controlled by the relay action, are available by reference to the disclosure of the audio-visual presentation system in the previously identified Sprinkle patent application.

As was hereinbefore indicated, switches 54 and 130 are actuated by drives imparted to the contact arms of these switches through their engagement with camming surfaces. Reference to FIGS. 2A and 2C reveal these surfaces on the outer periphery of a radial disc cam 230. Also, as previously indicated, cam 230 is rotatable when clutch engaging mechanism 80, shown in FIG. 1, is energized, and thus operable to transmit a drive from timing motor 120 to shaft 122 which is received in a central collar of the cam and secured thereto. However, rotation of cam 230 is limited to approximately a half turn clockwise, and a counterclockwise return thereof to a start position, as appears in FIGS. 2C and 2A, respectively. Setting this start position is an arcuate block 234 which is adjustably secured to the cam on a side flat thereof contiguous to the aforementioned camming surface 126. Block 234 is carried by cam displacements in a path crossed by a narrow bar 238 which projects from a wall 240 of an appertaining housing so as to intercept and stop the clock by engagement therewith. Adjustments of the block are made by loosening attaching screws 242 which traverse an arcuate slot 244 in the block, and resecuring the block with the screws at a location along the edge of camming surface 126. An operational starting point for the cam is determined by such an adjustment, as will hereinafter more fully appear. A coil spring 246 mounted by attachment at one end of housing wall 240 and at its other end to a stud 248 affixed in a side flat of cam 230 is thereby arranged to propel the cam counter to displacements thereof made by the motor drive. Thus, in FIG. 2A, illustrating an operational setting of the cam when cam shaft 122 is free from the motor drive, spring 246 acts to hold the cam quiescent by drawing its block 234 against stop bar 238.

Two sets of camming surfaces constituting the relevant configuration of cam 230 are characterized by their radial dimension from the axis of cam rotation at shaft 122. More specifically, camming surfaces 124 and 126, in addition to a further camming surface 250, are radially protracted, or high, with respect to other shorter radius, or low camming surfaces 252, 254, and 256, with which the high surfaces are alternately interspaced. The action of these camming surfaces proceeds in sequences wherein it is effective to monitor the cooperation of the aforementioned system apparatus with the sequence of control signals read out from the tape in recorder 20. A requisite synchronization between the effective response to the control signals originating at the tape recorder 20 and thejeffective response to the operation controlling action of cam 230 is assured since in actuality both the tape drive motor of the recorder and of cam driving timing motor 120 are energized in synchronism from a common a*c source such a standard 60 cycle a-c power wall outlet. In this connection each control signal provided to effect a slide change operation upon the completion of the presentation of the slide showing and its accompanying message, is recorded to permit the detection thereof to begin approximately 2 seconds before the upcoming slide is scheduled for presentation by projection. Although a slide change signal is continuous for 2 seconds, only about 0.1 of a second of its terminal portion acts to trigger a slide change operation which in turn requires approximately 1 second to obtain an appearance of the picture. With start button 206 actuated to effect operation of relay to where its contact arms are set as shown in dashed lines in FIG. 1, representing engagement with upper fixed contacts of the relay, such projector components as blower fan 16 and projection lamp 18, as well as tape recorder 20 are rendered operative. The subsequent detection on the tape of a slide change control signal gives rise to acurrent in the circuit including leads 31 and 32 which energizes lamp 40. Responding to light from lamp 40 photocell 36 activates circuit 46 triggering conduction in thyristor 42, and the circuit energizing clutch engaging mechanism is thus completed to a rectified and smoothed source of power by way of leads 96, 86, 84, 88, 90, 92, 94, and the connections to the thyristor power terminals. On the other hand, thyristor 44 does not become conductive even though photocell 38 also responds to the light from lamp 40 since initially this thyristors trigger circuit, which extends through leads 60, 56, 57, and 61, stands open at switch 54. Reference to the FIG. 2A showing of cam 230 as initially disposed reveals its-high surfaces 124 and 126 positioned where they open normally closed switch 54 and close normally open switch 130. Thus, thyristor 132 conducts, having been triggered in the circuit completed through closed switch 130, and energization of motor 120 is effectuated in the circuit extending from power source through leads 138, 134, 88, 90, 92, 136, and the power terminals of thyristor 132. 0

Cam 230 is steadily rotated clockwise, as it is viewed in the figures of the drawing, tensioning spring 246, since a timed drive from energized motor is transmitted by way of clutch engaging mechanism 80, also now energized. As long as the arm of switch 54 rides on high surface 124 of the cam the conduction of thyristor 44 is delayed, and slide change devices 12 remain ineffective. However, aftera predetermined time interval,

rotation of cam 230 positions its low surface 252, as ilfrustrated in FIG. 28, where the arm of switch 54 is permitted to effect closure of the switch. Conduction in thyristor 44 now occurs since itsv trigger circuit 48 completed through leads 57, 61, 60, 57 and switch 54, and a power supply. for energizing slide change devices 12 is established in a circuit including leads 62 and 64 connected to the thyristors power terminals. The energization of timing motor 120 is sustained since high cam surface 126 is relatively long and remains effective to maintain switch 130 closed as the cam continues to be displaced clockwise past the disposition thereof indicated in FIG. 2B. However, a valid slide change control signal ceases, having accomplished its mission,

concomitantly withadisplacement of the arm ofswitch 54 out of the cam dip of low surface 252 to high surface 250. Thyristors 42 and 44 becomes nonconducting due to the loss of light from lamp 40, with a consequential cessation of powerv to clutch engaging mechanism 80 along withthat suppliedto slide changing devices 12. Since a motor drive nolonger reaches cam shaft 122, tensioned spring 246 acts to rotate rapidly cam 230 counterclockwise, and restores the cam to an initial position thereof, as shown in FIG. 2A, when block 234 is stopped by bar 238. An unscheduled further slide change does not arise upon the momentary closure of switch 54 during reentry of its arm in the cam dip at surface 252 as the cam restores since a control signal is not present to energize lamp 40. Spurious signals during such closure would be redundant since devices 20 are then in an operative state, and such signals then are of no consequence. Evident from the foregoing is that the aforesaid interval between the start of the cams clockwise rotation and the subsequent closure of switch 54, which in effect defines the delay in triggering thyristor 44 following the initiation of a control signal, is variable by adjusting block 234 within the limits allowed by its slot 244, as was hereinbefore explained. Thus, the 2 seconds delay previously indicated for the disclosed embodiment may be made 1 second by a counterclockwise adjustment of block 234, as viewed in the figures of the drawing.

Following the onset of the concluding long control signal upon completionof the audio-visual presentation program, in the manner previously disclosed, lamp 40 is maintained in an energized state which it normally holds for a time to allow the advance of cam 230 to the disposition thereof illustrated in FIG. 2C. In the course 130 may, in some unusual instances, alternately open and close on camming surfaces 256 and 126, respectively, as spring 246 attempts to restore cam 230 counterclockwise against the friction of a gear train associated with motor 120, and the motor subsequently reoperates to rotate the cam clockwise again. After restoration of a slide to the slide carrier tray s compartment 80, the subsequent indexing of the tray, which resets its 0 compartment to the optical projection station of the projector, causes the tray carried magnet 162 to sweepinto alignment with coil 164, affixed to the projector casing, and give rise to a stop signal pulse in the circuit, comprising leads 166 and 168, to amplifier 170. Thus, thyristor 160 iscaused' to conduct in response to the activation of its trigger circuit by the light reaching photocell 182 thereof from lamp 180,

' which was energized in the output circuit of amplifier of this advance high cam surface 250 traverses the arm of switch 54 which thereafter comes to rest on low to open upon a transition thereof from engagement with high camming surface 126 to contact with low camming surface 256, is sufficiently long to remain in contact with the arm of switch 54 any time switch 130 is disposed to open. Accordingly, switch 54 remains projector. The length of cam surface 254 which has I traversed the arm of switch 54 before switch 130 starts 170 comprising leads 172 and 174. Electromagne't 196, now energized in the power circuit completed thereto through plus power lead 190, the power terminals of thyristor 160, lead 192, and negative power lead 200, operates relay to latch its contact'arms where they engage relay contacts 218 to 223, inclusive, as illustrated in FIG. 1 by the full line showing of these contact arms. Slide changing devices 20 and projection lamp 18 are consequently deactivated when their energizing circuits are thus interrupted by the separation of contact arms from relay contacts 72, 74, and 212, respectively.

However, blower fan 16 and tape recorder 20 remain activated following the change over of latching relay 70 as long as the long control signal remains effective to maintain the energization of lamp 40. Although breaking of the circuit path through relay contact 210 appears to disrupt current flow in a circuit enabling the application of ac. power source 260 for energization of blower fan 16 and tape recorder 20, and such interruption is in fact ineffective to stop the operation of these system components. An alternate enabling circuit to apply power source 260 is reestablished almost immediately by the relay contact arms which engage relay contacts 218, 219, and 220, and complete a current path for the energization of the enabling circuit from plus power supply on leads 262, 264, and 64, and by way of the power terminals of thyristor 44, now conductive, through leads 62, and 266, to negative power lead 268. Further inhibiting any critical deenergization of the system components are a slow acting relay in the aforesaid enabling circuit which provides a momentary hold on a-c source 260, and the momentum of the tape recorder elements which also acts briefly to carry the tape ahead during a possible temporary absence of applied power. Thus, with slide carrier tray 14 now held in its starting disposition, the concluding portion of the long control signal remains steadily effective to maintain the operation of blower fan 18, as well as tape recorder 20 which in turn supplies from its tape the remaining portion of the control signal. Upon reaching the end of the long control signal, after a requisite cooldown time, lamp 40 extinguishes, and conduction in thryristors 42 and 44 ceases since the related trigger circuits are inactivated when their photocells 36 and proved system are. restored to the initial state thereof,

including the tape recording employed herein, which is of the continuous type wherein the start of its messages with control signalsar'e reached immediately following the end of the long control signal read-out therefrom.

In the event picture transparency slides are placed in all 80 compartments of slide carrier tray 14, the time when a long control signal starts is normally coincidental with that in which an indexing drive rotates the tray to take an opaque slide in compartment to where it is aligned over the projectors optical axis. As was previously explained, this rotation of tray 14 displaces magnet 162 over coil 164 and gives rise to a signal which in this instance would trigger the changeover of latching relay 70 at a time when switch 54 is held open by engagement of its arm with camming surface 250. Consequently, the aforementioned alternate power circuit enabling energization of blower fan 16 and tape recorder 20, which becomes effective by reason of conduction in thyristor 44 in a circuit completed through latching relay contacts 218, 219, and 220, would fail to function as contemplated since thyristor 44 would now cease to conduct since it trigger circuit 48 is open at switch 54. A significantly slowed tape drive in recorder 20 occasioned by the resultant power shortage thereto would be accompanied by a frequency drop which in turn would weaken the long control signal available to energize lamp 40. Since a proper level of energization in lamp 40 would not be maintained in these circumstances this'lamp would dim and effectively cancel the response of photocells 36 and 38 thereto in their respective thyristor trigger circuits. Even though the release of cam 230 to its spring 246, when clutch engaging mechanism 80 deactivates upon failure of thyristor 42 to conduct, obtains the reclosure of switch 54 at camming surface 252, the nonreversible effect of theweakening light at lamp 40 would allow all circuits to deactivate quickly. To avoid this sort of accidental shut down of the audio-visual system an interlock circuit is provided in which switch 54 is shunted through contacts closed when relay 70 is actuated to its slidechanging stop latched condition. This circuit appears in FIG. 1 as arranged to by-pass switch 54 by way of leads 270 and 272 which extend from the respective power leads 57 and 56 to connections at a relay contact arm 273 and fixed contact 223 adapted to be engaged thereby, respectively. To dissociate the shunt circuit from the projector lamp energization circuit including leads 275, 276, and 277, redundant circuitry for this lamp which appears in the above-identified Sprinkle patent application as including leads between contact arm connectors 278 and 279, and between relay contact 214 and lead 277, is eliminated in this instance. Accordingly, in response to the stop signal initiated in coil 164, relay 70 returns to its standby latched condition, as indicated in FIG. 1 by the full line showing of its contact arms, and maintains the integrity of trigger circuit 48 of thyristor 44 through relay closure at contact 223 in the circuitry comprising leads 61, 57, 270, 272, 56 and 60, even though switch 54 is inadvertently held open. Upon the subsequent actuation of start button 206 to initiate a further system operation relay 70 relatches, as indicated by the dashed line showing of the relay contact arms in FIG. 1, the shunt circuit opens at contact 223, and switch 54 is free once more to monitor the slide changing functions of the system.

Fromthe foregoing it will be understood that the present invention protects a system operation from an improper control therein due to casual signals read from a tape recording which because of their form would otherwise precipitate the improper control. Thus, a time delay between any control signal start and the functional response thereto in the system, measured by the initial relative disposition of the arm of switch 54 on camming surface 124, is determined to exceed the likely duration of the longest expected one of such spurious control signals. Each valid control signal is therefore of a duration which exceeds this time delay,

and the recording thereof during tape preparation is begun at such time before the contemplated functional response thereto as would provide a significant reading thereof when a control signal is appropriate, Consequently, a spurious signal of control characteristics occurring before the reading of a valid signal from the recording is effective to initiate clockwise rotation of cam 230, but due to the shorter duration of such a spurious signal any cam displacement in response thereto falls short of placing low camming surface 252 at the arm of switch 54. The effects of spurious signals which occur during the reading of a valid control signal, or any rotary displacement of cam 230 in response thereto, are redundant and of the no consequence to proper operation of the system.

Typical of commercially available equipment having utility in the disclosed embodiment of the present invention are the Ektagraphic carousel projector made by Eastman Kodak Company of Rochester, New York, for a projector having a slide changing arrangement 10, the Viking standard stereo, stacked head, tape deck for tape recorder 20, the a-c synchronous, 4 RPM motor, equipped with a fast operating clutch, made by Hurst Company of Princeton, Indiana, for timing motor I and clutch engaging mechanism 80, the fast operating resistive type photo cell CL-707HL, made by Clairex Corporation, of New York, N.Y., for photo cells 36, 38, and 182, and the 50,000 hours CM8-80l light bulb made by Chicago Miniature Lamp Works, Chicago, Illinois, for lamps 40 and 180.

While a preferred form of the physical embodiment of the invention has been illustrated and described herein, it will be understood that the invention is not limited thereby, but is susceptible to change in form and detail. Exemplary alternative arrangements having utility in place of the described cam actuated switching structure include switching circuits controlled by photo cells placed to respond to light projected from inside a rotatable circular housing, or behind a rotatable disk, and at interspaced openings and blocking portions thereof whose lengths and dispositions are commensurate with that of the high and low camming surface of the described structure.

What is claimed is:

1. In an integrated electro-mechanical system having a in circuits of said apparatus, a signal discriminator operatively responsive to said generated signals. to preclude control of said apparatus functions byspuriousgenerated signals and enable such control by other generated signals, said signal discriminator comprising a circuit controller having a switching element displaceable in afirst predetermined direction from a preset point of departure therefor to a plurality of circuit conditioning. dispositions including a first range of dispositions thereof within a first predetermined interval of time during which spurious signals are likely to be generated and wherein said apparatus circuits are conditioned by reason of said first range of dispositions to prevent said apparatus functions, a second range of dispositions thereof within a second predetermined interval of time during which said other generated signals are extant and wherein said apparatus circuits are conditioned by reason of said second range of dispositions to effect a first predetermined sequence of said apparatus functions, and a third range of dispositions thereof within a third predetermined interval of time during which said other signals are also generated and wherein said apparatus circuits are conditioned by reason of said third range of dispositions to effect a second predetermined sequence of said apparatus functions, timed driving means adapted to displace said switching element in said first predetermine direction, I drive transfer means operable to apply said drive of said timed means for displacing said switching elementto saiddispositions thereof when activated in response to receipt of said generated signals in said apparatusicircuits, and means continually effective for applying a force driving said switching element in opposition to said transferred drive whereby said switching element is displaceable in a second predetermined direction toward said point of departure when said drive transfer means is deactivated.

2. in the system of claim 1, wherein said apparatus further comprises a transceiver having energizable circuit conditioning means activated in response to receipt therein of said generated signals, and dual circuitries responding to energization of said circuit conditioning means by transmitting through one of said dual circuitries an electrical power directing said activation of said drive transfer means, and through a second of said dual circuitries, when further conditioned in coordination with said effectuating control of said circuit controller, electrical power producing said sequences of apparatus functions.

3. In the system of claim 1, said discriminator having a circuit controller wherein said switching element is effective to determine the operative states of switches in said apparatus circuits, including a first switch adapted when closed to permit the activation of circuits facilitating the production of said apparatus functions 7.15 iiuriii 'ifi firifgrifih ii lfii eri ai KPiim iE preclude said circuits activation for said apparatus functions, and a second switch adapted when closed to permit the activation of circuits facilitating energization of said timed driving means and when open to preclude said circuits activation for said driving means energization, and thereby said switching element in said first range of dispositions thereof maintains said first switch open and said second switch closed, in said second range of dispositions maintains said first switch alternately closed and open and said second switch closed, and in said third range of dispositions maintains said first switch closed and said second switch alternately closed and open. i

4. In the system of claim 3, said discriminator having a circuit controller wherein said switching element comprises a generally circular member having irregular peripheral portions which are arranged to effect changes in said operative states of said switches in said apparatus, said member being rotatably displaceable by said timed driving means with respect to a fixed stop element at said point of departure, and means adjustably secured to said member so as to be movable therewith, said adjustably means being preset on said member to engage said fixed stop element at an initial position of said member in said first range of dispositions of said switching element whereby said first predetermined interval of time is determined.

5. In the system of claim 3, wherein said apparatus further comprises a transceiver having energizable circuit conditioning means activated in response to receipt therein of said generated signals, and dual cir cuitries responding to energization of said circuit conditioning means by transmitting through one of said dual circuitries an electrical power directing said activation of said drive transfer means, and through a second of said dual circuitries, when further conditioned in coordination with said efiectuating control of said circuit controller, electrical power producing said sequences of apparatus functions, a multi-contact relay settable for latching in first and second contact closing arrangements when energized by electrical power in a system starting and stopping circuits, respectively, another signal generating means operable to produce a further generated signal upon each incident of a predetermined disposition of elemental parts of said apparatus, whereby power supplied to said staring circuit upon closure of a starting switch therein gives rise to said first contact closing arrangement which in turn enable transmission of electrical power producing said sequences of apparatus functions, and power supplied to said stopping circuit in response to production of said further generated signal, gives rise to said second contact closing arrangement which in turn disables transmission of electrical power producing a predetermined portion of said sequence of apparatus functions, and an interlock circuit, adapted to shunt said first switch maintained by said dispositions of said switching element, having connections to contacts of said relay which in said first contact closing arrangement are maintained open to disable said shunt, and in said second contact closing arrangement are maintained closed to enable said shunt. 

1. In an integrated electro-mechanical system having an automatically operated apparatus and a signal generator supplying said apparatus with signals effective therein to control a sequence of apparatus functions which are determinable by conditions prevailing in circuits of said apparatus, a signal discriminator operatively responsive to said generated signals to preclude control of said apparatus functions by spurious generated signals and enable such control by other generated signals, said signal discriminator comprising a circuit controller having a switching element displaceable in a first predetermined direction from a preset point of Departure therefor to a plurality of circuit conditioning dispositions including a first range of dispositions thereof within a first predetermined interval of time during which spurious signals are likely to be generated and wherein said apparatus circuits are conditioned by reason of said first range of dispositions to prevent said apparatus functions, a second range of dispositions thereof within a second predetermined interval of time during which said other generated signals are extant and wherein said apparatus circuits are conditioned by reason of said second range of dispositions to effect a first predetermined sequence of said apparatus functions, and a third range of dispositions thereof within a third predetermined interval of time during which said other signals are also generated and wherein said apparatus circuits are conditioned by reason of said third range of dispositions to effect a second predetermined sequence of said apparatus functions, timed driving means adapted to displace said switching element in said first predetermined direction, drive transfer means operable to apply said drive of said timed means for displacing said switching element to said dispositions thereof when activated in response to receipt of said generated signals in said apparatus circuits, and means continually effective for applying a force driving said switching element in opposition to said transferred drive whereby said switching element is displaceable in a second predetermined direction toward said point of departure when said drive transfer means is deactivated.
 2. In the system of claim 1, wherein said apparatus further comprises a transceiver having energizable circuit conditioning means activated in response to receipt therein of said generated signals, and dual circuitries responding to energization of said circuit conditioning means by transmitting through one of said dual circuitries an electrical power directing said activation of said drive transfer means, and through a second of said dual circuitries, when further conditioned in coordination with said effectuating control of said circuit controller, electrical power producing said sequences of apparatus functions.
 3. In the system of claim 1, said discriminator having a circuit controller wherein said switching element is effective to determine the operative states of switches in said apparatus circuits, including a first switch adapted when closed to permit the activation of circuits facilitating the production of said apparatus functions in response to said generated signals and when open during said first predetermined interval of time to preclude said circuits activation for said apparatus functions, and a second switch adapted when closed to permit the activation of circuits facilitating energization of said timed driving means and when open to preclude said circuits activation for said driving means energization, and thereby said switching element in said first range of dispositions thereof maintains said first switch open and said second switch closed, in said second range of dispositions maintains said first switch alternately closed and open and said second switch closed, and in said third range of dispositions maintains said first switch closed and said second switch alternately closed and open.
 4. In the system of claim 3, said discriminator having a circuit controller wherein said switching element comprises a generally circular member having irregular peripheral portions which are arranged to effect changes in said operative states of said switches in said apparatus, said member being rotatably displaceable by said timed driving means with respect to a fixed stop element at said point of departure, and means adjustably secured to said member so as to be movable therewith, said adjustable means being preset on said member to engage said fixed stop element at an initial position of said member in said first range of dispositions of said switching element whereby said first predetermined iNterval of time is determined.
 5. In the system of claim 3, wherein said apparatus further comprises a transceiver having energizable circuit conditioning means activated in response to receipt therein of said generated signals, and dual circuitries responding to energization of said circuit conditioning means by transmitting through one of said dual circuitries an electrical power directing said activation of said drive transfer means, and through a second of said dual circuitries, when further conditioned in coordination with said effectuating control of said circuit controller, electrical power producing said sequences of apparatus functions, a multi-contact relay settable for latching in first and second contact closing arrangements when energized by electrical power in a system starting and stopping circuits, respectively, another signal generating means operable to produce a further generated signal upon each incident of a predetermined disposition of elemental parts of said apparatus, whereby power supplied to said starting circuit upon closure of a starting switch therein gives rise to said first contact closing arrangement which in turn enable transmission of electrical power producing said sequences of apparatus functions, and power supplied to said stopping circuit in response to production of said further generated signal, gives rise to said second contact closing arrangement which in turn disables transmission of electrical power producing a predetermined portion of said sequence of apparatus functions, and an interlock circuit, adapted to shunt said first switch maintained by said dispositions of said switching element, having connections to contacts of said relay which in said first contact closing arrangement are maintained open to disable said shunt, and in said second contact closing arrangement are maintained closed to enable said shunt. 